The three passengers were reportedly treated in hospital for minor whiplash. Urmson cites the object awareness video above, which displays the Google vehicle braking in a normal and natural fashion, while the vehicle behind it fails to decelerate.

The prang follows a non-crash with a Delphi robotic car in what initially seemed the beginning of an internecine tincandroid conflict.

Google's vehicles have been hit on 14 occasions since the start of its robot chauffeur project in 2009. Eleven of these were rear-enders, writes Urmon, "and not once has the self-driving car been the cause of the collision. Instead, the clear theme is human error and inattention".

"Our self-driving cars can pay attention to hundreds of objects at once, 360 degrees in all directions," writes Urmon, who gave a TED talk on 'How a driverless car sees the road', "and they never get tired, irritable or distracted".